Unprofessional company. Poor service

I wrote to this company on 21/12/2021 ti cancel my contract. They only acknowledged my cancelation on 05/02/2022. I called to confirm whether the cancelation had been effected and finalized and they confirmed that it was. However, since then, I have been receiving sms' from them demanding payment from me. Today I received one saying that they have now handed me over to the credit bureaus. I have tried to call them several times to try to resolve this but no one answers their phones. It's the most unprofessional service I have ever received from any company and would seriously advise against taking up a contract with them.